Project Summary The focus of this program is to create high-performance, low-cost, passive prosthetic knees that can accurately replicate physiological gait in multiple mobility scenarios. The product of this work will be knee technology that drastically enhances the mobility and quality of life for lower leg amputees in the developing world, while also providing a cost effective option with enhanced performance to developed world users. The foundation of this research is our novel method for determining the knee torque profile required for a low-mass prosthesis to replicate a given gait behavior, calculated from able-bodied kinematic and kinetic data for the same behavior. We have shown that these adjusted prosthesis torque profiles can be produced using only simple, low-cost, passive mechanical elements such as linear springs and friction dampers. This research program will entail measuring kinematic and kinetic data of able-bodied individuals performing activities of daily living. These data will be used to calculate the adjusted torque profiles required for a prosthetic knee to perform the same activities. We will then optimize a knee architecture that uses only simple, passive mechanical elements that can most accurately replicate all of the gait activities. An updated version of our knee design will be tested in a gait lab at Northwestern University, to correlate experiments with our theoretical model and refine its accuracy. Our knee will then be field tested in India with BMVSS Jaipur Foot. The project will culminate in a refined knee technology that is ready for larger-scale clinical testing and progression towards commercialization.